/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.library.string;

import org.apache.iotdb.udf.api.UDTF;
import org.apache.iotdb.udf.api.access.Row;
import org.apache.iotdb.udf.api.collector.PointCollector;
import org.apache.iotdb.udf.api.customizer.config.UDTFConfigurations;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameterValidator;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameters;
import org.apache.iotdb.udf.api.customizer.strategy.RowByRowAccessStrategy;
import org.apache.iotdb.udf.api.type.Type;

/**
 * This function does limited times of replacement of substring from an input series.
 */
public class UDTFStrReplace implements UDTF {

    private String target;
    private String replace;
    private int limit;
    private int offset;
    private boolean reverse;

    @Override
    public void validate(UDFParameterValidator validator) throws Exception {
        validator
                .validateInputSeriesNumber(1)
                .validateInputSeriesDataType(0, Type.TEXT)
                .validate(
                        target -> ((String) target).length() > 0,
                        "target should not be empty",
                        validator.getParameters().getString("target"))
                .validate(
                        limit -> (int) limit >= -1,
                        "limit has to be -1 for replacing all matches or non-negative integers for limited"
                                + " times.",
                        validator.getParameters().getIntOrDefault("limit", -1))
                .validate(
                        offset -> (int) offset >= 0,
                        "offset has to be non-negative to skip first several matches.",
                        validator.getParameters().getIntOrDefault("offset", 0));
    }

    @Override
    public void beforeStart(UDFParameters udfParameters, UDTFConfigurations udtfConfigurations)
            throws Exception {
        target = udfParameters.getString("target");
        replace = udfParameters.getString("replace");
        limit = udfParameters.getIntOrDefault("limit", -1);
        offset = udfParameters.getIntOrDefault("offset", 0);
        reverse = udfParameters.getBooleanOrDefault("reverse", false);
        udtfConfigurations.setAccessStrategy(new RowByRowAccessStrategy()).setOutputDataType(Type.TEXT);
    }

    @Override
    public void transform(Row row, PointCollector collector) throws Exception {
        String origin = row.getString(0);
        String result;
        if (reverse) {
            int endIndex = origin.length();
            int count = 0;
            while (count < offset) {
                int matchIndex = origin.lastIndexOf(target, endIndex - 1);
                if (matchIndex == -1) {
                    break;
                } else {
                    endIndex = matchIndex;
                    count++;
                }
            }
            // no enough matches to skip
            if (count < offset) {
                endIndex = 0;
            }
            String suffix = origin.substring(endIndex);
            while (count < offset + limit) {
                int matchIndex = origin.lastIndexOf(target, endIndex - 1);
                if (matchIndex == -1) {
                    break;
                } else {
                    endIndex = matchIndex;
                    count++;
                }
            }
            // replace all left matches
            if (limit == -1 || count < offset + limit) {
                endIndex = 0;
            }
            String prefix = origin.substring(0, endIndex);
            result =
                    prefix
                            .concat(
                                    origin
                                            .substring(endIndex, origin.length() - suffix.length())
                                            .replace(target, replace))
                            .concat(suffix);
        } else {
            int fromIndex = 0;
            int count = 0;
            while (count < offset) {
                int matchIndex = origin.indexOf(target, fromIndex);
                if (matchIndex == -1) {
                    break;
                } else {
                    fromIndex = matchIndex + target.length();
                    count++;
                }
            }
            // no enough matches to skip
            if (count < offset) {
                fromIndex = origin.length();
            }
            String prefix = origin.substring(0, fromIndex);
            while (count < offset + limit) {
                int matchIndex = origin.indexOf(target, fromIndex);
                if (matchIndex == -1) {
                    break;
                } else {
                    fromIndex = matchIndex + target.length();
                    count++;
                }
            }
            // replace all left matches
            if (limit == -1 || count < offset + limit) {
                fromIndex = origin.length();
            }
            String suffix = origin.substring(fromIndex);
            result =
                    prefix
                            .concat(origin.substring(prefix.length(), fromIndex).replace(target, replace))
                            .concat(suffix);
        }
        collector.putString(row.getTime(), result);
    }
}
